Shielded electrical cable

ABSTRACT

A shielded electrical cable includes a conductor set and a shielding film. The conductor set includes one or more substantially parallel longitudinal insulated conductors. The shielding film includes a cover portion partially covering the conductor set, and parallel portions extending from both sides of the conductor set.

TECHNICAL FIELD

The present disclosure relates generally to shielded electrical cablesfor the transmission of electrical signals. In particular, the presentinvention relates to shielded electrical cables that can bemass-terminated and provide high speed electrical properties.

BACKGROUND

Electrical cables for transmission of electrical signals are well known.One common type of electrical cable is a coaxial cable. Coaxial cablesgenerally include an electrically conductive wire surrounded by aninsulator. The wire and insulator are surrounded by a shield, and thewire, insulator, and shield are surrounded by a jacket. Another commontype of electrical cable is a shielded electrical cable comprising oneor more insulated signal conductors surrounded by a shielding layerformed, for example, by a metal foil. To facilitate electricalconnection of the shielding layer, a further un-insulated conductor issometimes provided between the shielding layer and the insulation of thesignal conductor or conductors. Both these common types of electricalcable normally require the use of specifically designed connectors fortermination and are often not suitable for the use of mass-terminationtechniques, i.e., the simultaneous connection of a plurality ofconductors to individual contact elements, such as, e.g., electricalcontacts of an electrical connector or contact elements on a printedcircuit board. Although electrical cables have been developed tofacilitate these mass-termination techniques, these cables often havelimitations in the ability to mass-produce them, in the ability toprepare their termination ends, in their flexibility, and in theirelectrical performance. In view of the advancements in high speedelectrical and electronic components, a continuing need exists forelectrical cables that are capable of transmitting high speed signals,facilitate mass-termination techniques, are cost-effective, and can beused in a large number of applications.

SUMMARY

In one aspect, the present invention provides a shielded electricalcable including a conductor set and a shielding film. The conductor setincludes one or more substantially parallel longitudinal insulatedconductors. The shielding film includes a cover portion partiallycovering the conductor set, and parallel portions extending from bothsides of the conductor set.

In another aspect, the present invention provides a shielded electricalcable including a plurality of spaced apart conductor sets arrangedgenerally in a single plane and a shielding film. Each conductor setincludes one or more substantially parallel longitudinal insulatedconductors. The shielding film includes a plurality of cover portionspartially covering the conductor sets, and a parallel portion disposedbetween adjacent conductor sets and configured to electrically isolatethe adjacent conductor sets from each other.

The above summary of the present invention is not intended to describeeach disclosed embodiment or every implementation of the presentinvention. The Figures and detailed description that follow below moreparticularly exemplify illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary embodiment of a shieldedelectrical cable according to an aspect of the present invention.

FIGS. 2a-2e are front cross-sectional views of five other exemplaryembodiments of a shielded electrical cable according to aspects of thepresent invention.

FIG. 3 is a perspective view of two shielded electrical cables of FIG. 1terminated to a printed circuit board.

FIGS. 4a-4d are top views of an exemplary termination process of ashielded electrical cable according to an aspect of the presentinvention.

FIG. 5 is a top view of another exemplary embodiment of a shieldedelectrical cable according to an aspect of the present invention.

FIG. 6 is a top view of another exemplary embodiment of a shieldedelectrical cable according to an aspect of the present invention.

FIGS. 7a-7d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable according to aspects of thepresent invention.

FIGS. 8a-8c are front cross-sectional views of three other exemplaryembodiments of a shielded electrical cable according to aspects of thepresent invention.

FIGS. 9a-9b are top and partially cross-sectional front views,respectively, of an exemplary embodiment of an electrical assemblyaccording to an aspect of the present invention terminated to a printedcircuit board.

FIGS. 10a-10e and 10f-10g are perspective and front cross-sectionalviews, respectively, illustrating an exemplary method of making ashielded electrical cable according to an aspect of the presentinvention.

FIGS. 11a-11c are front cross-sectional views illustrating a detail ofan exemplary method of making a shielded electrical cable according toan aspect of the present invention.

FIGS. 12a-12b are a front cross-sectional view of another exemplaryembodiment of a shielded electrical cable according to an aspect of thepresent invention and a corresponding detail view, respectively.

FIGS. 13a-13b are front cross-sectional views of two other exemplaryembodiments of a shielded electrical cable according to an aspect of thepresent invention.

FIGS. 14a-14b are front cross-sectional views of two other exemplaryembodiments of a shielded electrical cable according to an aspect of thepresent invention.

FIGS. 15a-15c are front cross-sectional views of three other exemplaryembodiments of a shielded electrical cable according to aspects of thepresent invention.

FIGS. 16a-16g are front cross-sectional detail views illustrating sevenexemplary embodiments of a parallel portion of a shielded electricalcable according to aspects of the present invention.

FIGS. 17a-17b are front cross-sectional detail views of anotherexemplary embodiment of a parallel portion of a shielded electricalcable according to an aspect of the present invention.

FIG. 18 is a front cross-sectional detail view of another exemplaryembodiment of a shielded electrical cable according to an aspect of thepresent invention in a bent configuration.

FIG. 19 is a front cross-sectional detail view of another exemplaryembodiment of a shielded electrical cable according to an aspect of thepresent invention.

FIGS. 20a-20f are front cross-sectional detail views illustrating sixother exemplary embodiments of a parallel portion of a shieldedelectrical cable according to aspects of the present invention.

FIG. 21a-21b are front cross-sectional views of two other exemplaryembodiments of a shielded electrical cable according to aspects of thepresent invention.

FIG. 22 is a graph comparing the electrical isolation performance of anexemplary embodiment of a shielded electrical cable according to anaspect of the present invention to the electrical isolation performanceof a conventional electrical cable.

FIG. 23 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable according to an aspect of the presentinvention.

FIG. 24 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable according to an aspect of the presentinvention.

FIG. 25 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable according to an aspect of the presentinvention.

FIG. 26a-26d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable according to aspects of thepresent invention.

FIG. 27 is a front cross-sectional view of another exemplary embodimentof a shielded electrical cable according to an aspect of the presentinvention.

FIG. 28a-28d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable according to aspects of thepresent invention.

FIG. 29a-29d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable according to aspects of thepresent invention.

DETAILED DESCRIPTION

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings that form a part hereof.The accompanying drawings show, by way of illustration, specificembodiments in which the invention may be practiced. It is to beunderstood that other embodiments may be utilized, and structural orlogical changes may be made without departing from the scope of thepresent invention. The following detailed description, therefore, is notto be taken in a limiting sense, and the scope of the invention isdefined by the appended claims.

Referring now to the Figures, FIG. 1 illustrates an exemplary embodimentof a shielded electrical cable according to an aspect of the presentinvention. Shielded electrical cable 2 includes a plurality of spacedapart conductor sets 4 arranged generally in a single plane. Eachconductor set includes two substantially parallel longitudinal insulatedconductors 6. Insulated conductors 6 may include insulated signal wires,insulated power wires, or insulated ground wires. Two generally parallelshielding films 8 are disposed around conductor sets 4. A conformableadhesive layer 10 is disposed between shielding films 8 and bondsshielding films 8 to each other on both sides of each conductor set 4.In one embodiment, conductor sets 4 have a substantially curvilinearcross-sectional shape, and shielding films 8 are disposed aroundconductor sets 4 such as to substantially conform to and maintain thecross-sectional shape. Maintaining the cross-sectional shape maintainsthe electrical characteristics of conductor sets 4 as intended in thedesign of conductor sets 4. This is an advantage over some conventionalshielded electrical cables where disposing a conductive shield around aconductor set changes the cross-sectional shape of the conductor set.

Although in the embodiment illustrated in FIG. 1, each conductor set 4includes two insulated conductors 6, in other embodiments, eachconductor set 4 may include one or more insulated conductors 6. Forexample, instead of shielded electrical cable 2 including four conductorsets 4 each including two insulated conductors 6 as shown in FIG. 1,shielded electrical cable 2 may include one conductor set 4 includingeight insulated conductors 6, or eight conductor sets 4 each includingone insulated conductor 6. This flexibility in arrangements of conductorsets 4 and insulated conductors 6 allows shielded electrical cable 2 tobe configured suitable for the intended application. For example,conductor sets 4 and insulated conductors 6 may be configured to form amultiple twinaxial cable, i.e., multiple conductor sets 4 each includingtwo insulated conductors 6, a multiple coaxial cable, i.e., multipleconductor sets each including one insulated conductor 6, or acombination thereof. In other embodiments, a conductor set 4 may furtherinclude a conductive shield (not shown) disposed around the one or moreinsulated conductors 6, and an insulative jacket (not shown) disposedaround the conductive shield.

In the embodiment illustrated in FIG. 1, shielded electrical cable 2further includes optional longitudinal ground conductors 12. Groundconductors 12 may include ground wires or drain wires. Ground conductors12 are spaced apart from and extend in substantially the same directionas insulated conductors 6. Conductor sets 4 and ground conductors 12 arearranged generally in a single plane. Shielding films 8 are disposedaround ground conductors 12 and conformable adhesive layer 10 bondsshielding films 8 to each other on both sides of ground conductors 12.Ground conductors 12 may electrically contact at least one of shieldingfilms 8.

FIGS. 2a-2e illustrate various exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention. FIGS.2a-2e are specifically intended to illustrate various examples ofarrangements of conductors disposed between two shielding films.

Referring to FIG. 2a , shielded electrical cable 102 includes a singleconductor set 104. Conductor set 104 includes a single longitudinalinsulated conductor 106. Two generally parallel shielding films 108 aredisposed around conductor set 104. A conformable adhesive layer 110 isdisposed between shielding films 108 and bonds shielding films 108 toeach other on both sides of conductor set 104. Shielded electrical cable102 further includes optional longitudinal ground conductors 112. Groundconductors 112 are spaced apart from and extend in substantially thesame direction as insulated conductor 106. Conductor set 104 and groundconductors 112 are arranged generally in a single plane. Shielding films108 are disposed around ground conductors 112 and conformable adhesivelayer 110 bonds shielding films 108 to each other on both sides ofground conductors 112. Ground conductors 112 may electrically contact atleast one of shielding films 108. Insulated conductor 106 is effectivelyarranged in a coaxial or single ended cable arrangement.

Referring to FIG. 2b , shielded electrical cable 202 is similar toshielded electrical cable 102 illustrated in FIG. 2a . Where shieldedelectrical cable 102 includes a single conductor set 104 including asingle longitudinal insulated conductor 106, shielded electrical cable202 includes a single conductor set 204 including two substantiallyparallel longitudinal insulated conductors 206. Insulated conductors 206are arranged generally in a single plane and effectively in a twinaxialor differential pair cable arrangement.

Referring to FIG. 2c , shielded electrical cable 302 is similar toshielded electrical cable 102 illustrated in FIG. 2a . Where shieldedelectrical cable 102 includes a single conductor set 104 including asingle longitudinal insulated conductor 106, shielded electrical cable302 includes a single conductor set 304 including two longitudinalinsulated conductors 306. Insulated conductors 306 are arrangedeffectively in a twisted pair cable arrangement, whereby insulatedconductors 306 twist around each other in longitudinal direction.

Referring to FIG. 2d , shielded electrical cable 402 is similar toshielded electrical cable 102 illustrated in FIG. 2a . Where shieldedelectrical cable 102 includes a single conductor set 104 including asingle longitudinal insulated conductor 106, shielded electrical cable402 includes a single conductor set 404 including four longitudinalinsulated conductors 406. Insulated conductors 406 are arrangedeffectively in a quad cable arrangement, whereby insulated conductors406 may twist around each other in longitudinal direction, or may besubstantially parallel.

Referring back to FIGS. 2a-2d , further embodiments of shieldedelectrical cables according to aspects of the present invention mayinclude a plurality of spaced apart conductor sets 104, 204, 304 or 404,or combinations thereof, arranged generally in a single plane.Optionally, the shielded electrical cables may include a plurality ofground conductors 112 spaced apart from and extending generally in thesame direction as the insulated conductors of the conductor sets,wherein the conductor sets and ground conductors are arranged generallyin a single plane. FIG. 2e illustrates an exemplary embodiment of such ashielded electrical cable.

Referring to FIG. 2e , shielded electrical cable 502 includes aplurality of spaced apart conductor sets 104, 204 arranged generally ina single plane. Shielded electrical cable 502 further includes optionalground conductors 112 disposed between conductor sets 104, 204 and atboth ends of shielded electrical cable 502. Two generally parallelshielding films 508 are disposed around conductor sets 104, 204 andground conductors 112. A conformable adhesive layer 510 is disposedbetween shielding films 508 and bonds shielding films 508 to each otheron both sides of each conductor set 104, 204 and each ground conductor.Shielded electrical cable 502 includes a combination of coaxial cablearrangements (conductor sets 104) and a twinaxial cable arrangement(conductor set 204) and may therefore be referred to as a hybrid cablearrangement.

FIG. 3 illustrates two shielded electrical cables 2 terminated to aprinted circuit board 14. Because insulated conductors 6 and groundconductors 12 are arranged generally in a single plane, shieldedelectrical cables 2 are well suited for mass-stripping, i.e., thesimultaneous stripping of shielding films 8 and insulated conductors 6,and mass-termination, i.e., the simultaneous terminating of the strippedends of insulated conductors 6 and ground conductors 12, which allows amore automated cable assembly process. This is an advantage of theshielded electrical cables according to aspects of the presentinvention. In FIG. 3, the stripped ends of insulated conductors 6 andground conductors 12 are terminated to contact elements 16 on printedcircuit board 14. In other embodiments, the stripped ends of insulatedconductors 6 and ground conductors 12 may be terminated to any suitableindividual contact elements of any suitable termination point, such as,e.g., electrical contacts of an electrical connector.

FIGS. 4a-4d illustrate an exemplary termination process of shieldedelectrical cable 2 to printed circuit board 14. This termination processcan be a mass-termination process and includes the steps of stripping(illustrated in FIGS. 4a-4b ), aligning (illustrated in FIG. 4c ), andterminating (illustrated in FIG. 4d ). When forming shielded electricalcable 2, the arrangement of conductor sets 4, insulated conductors 6,and ground conductors 12 of shielded electrical cable 2 may be matchedto the arrangement of contact elements 16 on printed circuit board 14,which would eliminate any significant manipulation of the end portionsof shielded electrical cable 2 during alignment or termination.

In the step illustrated in FIG. 4a , an end portion 8 a of shieldingfilms 8 is removed. Any suitable method may be used, such as, e.g.,mechanical stripping or laser stripping. This step exposes an endportion of insulated conductors 6 and ground conductors 12. In oneaspect, mass-stripping of end portion 8 a of shielding films 8 ispossible because they form an integrally connected layer that isseparate from the insulation of insulated conductors 6. Removingshielding films 8 from insulated conductors 6 allows protection againstelectrical shorting at these locations and also provides independentmovement of the exposed end portions of insulated conductors 6 andground conductors 12. In the step illustrated in FIG. 4b , an endportion 6 a of the insulation of insulated conductors 6 is removed. Anysuitable method may be used, such as, e.g., mechanical stripping orlaser stripping. This step exposes an end portion of the conductor ofinsulated conductors 6. In the step illustrated in FIG. 4c , shieldedelectrical cable 2 is aligned with printed circuit board 14 such thatthe end portions of the conductors of insulated conductors 6 and the endportions of ground conductors 12 of shielded electrical cable 2 arealigned with contact elements 16 on printed circuit board 14. In thestep illustrated in FIG. 4d , the end portions of the conductors ofinsulated conductors 6 and the end portions of ground conductors 12 ofshielded electrical cable 2 are terminated to contact elements 16 onprinted circuit board 14. Examples of suitable termination methods thatmay be used include soldering, welding, crimping, mechanical clamping,and adhesively bonding, to name a few.

FIG. 5 illustrates another exemplary embodiment of a shielded electricalcable according to an aspect of the present invention. Shieldedelectrical cable 602 is similar to shielded electrical cable 2illustrated in FIG. 1. In addition, shielded electrical cable 602includes a plurality of longitudinal splits 18 disposed betweenconductor sets 4. Splits 18 separate individual conductor sets 4 atleast along a portion of the length of shielded electrical cable 602,thereby increasing at least the lateral flexibility of shieldedelectrical cable 602. This allows shielded electrical cable 602 to beplaced more easily into a curvilinear outer jacket, e.g. In otherembodiments, splits 18 may be placed such as to separate individual ormultiple conductor sets 4 and ground conductors 12. To maintain thespacing of conductor sets 4 and ground conductors 12, splits 18 may bediscontinuous along the length of shielded electrical cable 602. Tomaintain the spacing of conductor sets 4 and ground conductors 12 in atleast one end portion A of shielded electrical cable 602 and therebymaintaining mass-termination capability, splits 18 may not extend intoone or both end portions A. Splits 18 may be formed in shieldedelectrical cable 602 using any suitable method, such as, e.g., lasercutting or punching. Instead of or in combination with longitudinalsplits, other suitable shapes of openings may be formed in shieldedelectrical cable 602, such as, e.g., holes, e.g., to increase at leastthe lateral flexibility of shielded electrical cable 602.

FIG. 6 illustrates another exemplary embodiment of a shielded electricalcable according to an aspect of the present invention. Shieldedelectrical cable 702 is similar to shielded electrical cable 602illustrated in FIG. 5. Effectively, in shielded electrical cable 702,one of conductor sets 4 is replaced by two ground conductors 12.Shielded electrical cable 702 includes longitudinal splits 18 and 18′.Split 18 separates individual conductor sets 4 along a portion of thelength of shielded electrical cable 702 and does not extend into endportions A of shielded electrical cable 702. Split 18′ separatesindividual conductor sets 4 along the length of shielded electricalcable 702 and extends into end portions A of shielded electrical cable702, which effectively splits shielded electrical cable 702 into twoindividual shielded electrical cables 702′, 702″. Shielding films 8 andground conductors 12 provide an uninterrupted ground plane in each ofthe individual shielded electrical cables 702′, 702″. This exemplaryembodiment illustrates the advantage of the parallel processingcapability of the shielded electrical cables according to aspects of thepresent invention, whereby multiple shielded electrical cables may beformed simultaneously.

FIGS. 7a-7d illustrate four other exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention. FIGS.7a-7e are specifically intended to illustrate various examples ofconstructions of the shielding films of the shielded electrical cables.In one aspect, at least one of the shielding films may include aconductive layer and a non-conductive polymeric layer. The conductivelayer may include any suitable conductive material, including but notlimited to copper, silver, aluminum, gold, and alloys thereof. Thenon-conductive polymeric layer may include any suitable polymericmaterial, including but not limited to polyester, polyimide,polyamide-imide, polytetrafluoroethylene, polypropylene, polyethylene,polyphenylene sulfide, polyethylene naphthalate, polycarbonate, siliconerubber, ethylene propylene diene rubber, polyurethane, acrylates,silicones, natural rubber, epoxies, and synthetic rubber adhesive. Thenon-conductive polymeric layer may include one or more additives and/orfillers to provide properties suitable for the intended application. Inanother aspect, at least one of the shielding films may include alaminating adhesive layer disposed between the conductive layer and thenon-conductive polymeric layer. In another aspect, at least one of theshielding films may include a stand-alone conductive film. Theconstruction of the shielding films may be selected based on a number ofdesign parameters suitable for the intended application, such as, e.g.,flexibility, electrical performance, and configuration of the shieldedelectrical cable (such as, e.g., presence and location of groundconductors). In one embodiment, the shielding films include anintegrally formed shielding film. In one embodiment, the shielding filmshave a thickness in the range of 0.01 mm to 0.05 mm. The shielding filmsprovide isolation, shielding, and precise spacing between the conductorsets, and enable a more automated and lower cost cable manufacturingprocess. In addition, the shielding films prevent a phenomenon known as“signal suck-out” or resonance, whereby high signal attenuation occursat a particular frequency range. This phenomenon typically occurs inconventional shielded electrical cables where a conductive shield iswrapped around a conductor set.

Referring to FIG. 7a , shielded electrical cable 802 includes a singleconductor set 804. Conductor set 804 includes two substantially parallellongitudinal insulated conductors 806. Two generally parallel shieldingfilms 808 are disposed around conductor set 804. Shielding films 808include a conformable adhesive layer 810 that bonds shielding films 808to each other on both sides of conductor set 804. Insulated conductors806 are arranged generally in a single plane and effectively in atwinaxial or differential pair cable arrangement. Shielding films 808include a conductive layer 808 a and a non-conductive polymeric layer808 b. Non-conductive polymeric layer 808 b faces insulated conductors806. Conductive layer 808 a may be deposited onto non-conductivepolymeric layer 808 b using any suitable method.

Referring to FIG. 7b , shielded electrical cable 902 includes a singleconductor set 904. Conductor set 904 includes two substantially parallellongitudinal insulated conductors 906. Two generally parallel shieldingfilms 908 are disposed around conductor set 904. Shielding films 908include a conformable adhesive layer 910 that bonds shielding films 908to each other on both sides of conductor set 904. Insulated conductors906 are arranged generally in a single plane and effectively in atwinaxial or differential pair cable arrangement. Shielding films 908include a conductive layer 908 a and a non-conductive polymeric layer908 b. Conductive layer 908 a faces insulated conductors 906. Conductivelayer 908 a may be deposited onto non-conductive polymeric layer 908 busing any suitable method.

Referring to FIG. 7c , shielded electrical cable 1002 includes a singleconductor set 1004. Conductor set 1004 includes two substantiallyparallel longitudinal insulated conductors 1006. Two generally parallelshielding films 1008 are disposed around conductor set 1004. Shieldingfilms 1008 include a conformable adhesive layer 1010 that bondsshielding films 1008 to each other on both sides of conductor set 1004.Insulated conductors 1006 are arranged generally in a single plane andeffectively in a twinaxial or differential pair cable arrangement.Shielding films 1008 include a stand-alone conductive film.

Referring to FIG. 7d , shielded electrical cable 1102 includes a singleconductor set 1104. Conductor set 1104 includes two substantiallyparallel longitudinal insulated conductors 1106. Two generally parallelshielding films 1108 are disposed around conductor set 1104. Shieldingfilms 1108 include a conformable adhesive layer 1110 that bondsshielding films 1108 to each other on both sides of conductor set 1104.Insulated conductors 1106 are arranged generally in a single plane andeffectively in a twinaxial or differential pair cable arrangement.Shielding films 1108 include a conductive layer 1108 a, a non-conductivepolymeric layer 1108 b, and a laminating adhesive layer 1108 c disposedbetween conductive layer 1108 a and non-conductive polymeric layer 1108b, thereby laminating conductive layer 1108 a to non-conductivepolymeric layer 1108 b. Conductive layer 1108 a faces insulatedconductors 1106.

Referring back to FIG. 1, conformable adhesive layer 10 of shieldedelectrical cable 2 is disposed between shielding films 8 and bondsshielding films 8 to each other on both sides of each conductor set 4.In one embodiment, conformable adhesive layer 10 may be disposed on oneof shielding films 8. In another embodiment, conformable adhesive layer10 may be disposed on both shielding films 8. Conformable adhesive layer10 may include an insulative adhesive and provide an insulative bondbetween shielding films 8. Optionally, conformable adhesive layer 10 mayprovide an insulative bond between at least one of shielding films 8 andinsulated conductors 6, and between at least one of shielding films 8and ground conductors 12. Conformable adhesive layer 10 may include aconductive adhesive and provide a conductive bond between shieldingfilms 8. Optionally, conformable adhesive layer 10 may provide aconductive bond between at least one of shielding films 8 and groundconductors 12. Suitable conductive adhesives include conductiveparticles to provide the flow of electrical current. The conductiveparticles can be any of the types of particles currently used, such asspheres, flakes, rods, cubes, amorphous, or other particle shapes. Theymay be solid or substantially solid particles such as carbon black,carbon fibers, nickel spheres, nickel coated copper spheres,metal-coated oxides, metal-coated polymer fibers, or other similarconductive particles. These conductive particles can be made fromelectrically insulating materials that are plated or coated with aconductive material such as silver, aluminum, nickel, or indiumtin-oxide. The metal-coated insulating material can be substantiallyhollow particles such as hollow glass spheres, or may comprise solidmaterials such as glass beads or metal oxides. The conductive particlesmay be on the order of several tens of microns to nanometer sizedmaterials such as carbon nanotubes. Suitable conductive adhesives mayalso include a conductive polymeric matrix. In one aspect, conformableadhesive layer 10 may include a continuous adhesive layer extendingalong the entire length and width of shielding films 8. In anotheraspect, conformable adhesive layer 10 may include a discontinuousadhesive layer. For example, conformable adhesive layer 10 may bepresent only in some portions along the length or width of shieldingfilms 8. In one embodiment, discontinuous adhesive layer 10 includes aplurality of longitudinal adhesive stripes that are disposed, e.g., onboth sides of each conductor set 4 and ground conductors 12. In oneembodiment, conformable adhesive layer 10 includes at least one of apressure sensitive adhesive, a hot melt adhesive, a thermoset adhesive,and a curable adhesive. In one embodiment, conformable adhesive layer 10is configured to provide a bond between shielding films 8 that issubstantially stronger than a bond between one or more insulatedconductor 6 and shielding films 8. This may be achieved, e.g., byselecting the adhesive formulation accordingly. An advantage of thisadhesive configuration is that shielding films 8 are readily strippablefrom the insulation of insulated conductors 6. In another embodiment,conformable adhesive layer 10 is configured to provide a bond betweenshielding films 8 and a bond between one or more insulated conductor 6and shielding films 8 that are substantially equally strong. Anadvantage of this adhesive configuration is that insulated conductors 6are anchored between shielding films 8. On bending shielded electricalcable 2, this allows for little relative movement and therefore reducesthe likelihood of buckling of shielding films 8. Suitable bond strengthsmay be chosen based on the intended application. In one embodiment,conformable adhesive layer 10 has a thickness of less than about 0.13mm. In a preferred embodiment, conformable adhesive layer 10 has athickness of less than about 0.05 mm.

Conformable adhesive layer 10 may conform to achieve desired mechanicaland electrical performance characteristics of shielded electrical cable2. In one aspect, conformable adhesive layer 10 may conform to bethinner between shielding films 8 in areas between conductor sets 4,which increases at least the lateral flexibility of shielded electricalcable 2. This allows shielded electrical cable 2 to be placed moreeasily into a curvilinear outer jacket, e.g. In another aspect,conformable adhesive layer 10 may conform to be thicker in areasimmediately adjacent conductor sets 4 and substantially conform toconductor sets 4. This increases the mechanical strength and enablesforming a curvilinear shape of shielding films 8 in these areas, whichincreases the durability of shielded electrical cable 2, e.g., duringflexing of the cable. In addition, this helps to maintain the positionand spacing of insulated conductors 6 relative to shielding films 8along the length of shielded electrical cable 2, which results inuniform impedance and superior signal integrity of shielded electricalcable 2. In another aspect, conformable adhesive layer 10 may conform toeffectively be partially of completely removed between shielding films 8in areas between conductor sets 4. As a result, shielding films 8electrically contact each other in these areas, which increases theelectrical performance of shielded electrical cable 2. In anotheraspect, conformable adhesive layer 10 may conform to effectively bepartially of completely removed between at least one of shielding films8 and ground conductors 12. As a result, ground conductors 12electrically contact at least one of shielding films 8 in these areas,which increases the electrical performance of shielded electrical cable2. Even if a thin conformable adhesive layer 10 exists between at leastone of shielding films 8 and ground conductors 12, asperities on groundconductors 12 may break through conformable adhesive layer 10 toestablish electrical contact as intended.

FIGS. 8a-8c illustrate three other exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention. FIGS.8a-8c are specifically intended to illustrate examples of the placementof ground conductors in the shielded electrical cables. An aspect of ashielded electrical cable is proper grounding of the shield. Shieldedelectrical cables according to aspects of the present invention can begrounded in a number of ways. In one aspect, the ground conductorselectrically contact at least one of the shielding films such thatgrounding the ground conductors also grounds the shielding films. Inthis arrangement, the ground conductors may also be referred to as“drain wires”. In another aspect, the ground conductors do notelectrically contact the shielding films, but are individual elements inthe cable construction that may be independently terminated to anysuitable individual contact element of any suitable termination point,such as, e.g., a contact element on a printed circuit board. In thisarrangement, the ground conductors may also be referred to as “groundwires”. FIG. 8a illustrates an exemplary embodiment of a shieldedelectrical cable according to an aspect of the present invention whereinthe ground conductors are positioned external to the shielding films.FIGS. 8b-8c illustrate two exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention whereinthe ground conductors are positioned between the shielding films, andmay be included in the conductor set. One or more ground conductors maybe placed in any suitable position external to the shielding films,between the shielding films, or a combination of both.

Referring to FIG. 8a , shielded electrical cable 1202 includes a singleconductor set 1204. Conductor set 1204 includes two substantiallyparallel longitudinal insulated conductors 1206. Two generally parallelshielding films 1208 are disposed around conductor set 1204. Aconformable adhesive layer 1210 is disposed between shielding films 1208and bonds shielding films 1208 to each other on both sides of conductorset 1204. Insulated conductors 1206 are arranged generally in a singleplane and effectively in a twinaxial or differential pair cablearrangement. Shielded electrical cable 1202 further includes a pluralityof ground conductors 1212 positioned external to shielding films 1208.Ground conductors 1212 are placed over, under, and on both sides ofconductor set 1204. Optionally, shielded electrical cable 1202 includesprotective films 1220 surrounding shielding films 1208 and groundconductors 1212. Protective films 1220 include a protective layer 1220 aand an adhesive layer 1220 b bonding protective layer 1220 a toshielding films 1208 and ground conductors 1212. Alternatively,shielding films 1208 and ground conductors 1212 may be surrounded by anouter conductive shield, such as, e.g., a conductive braid, and an outerinsulative jacket (not shown).

Referring to FIG. 8b , shielded electrical cable 1302 includes a singleconductor set 1304. Conductor set 1304 includes two substantiallyparallel longitudinal insulated conductors 1306. Two generally parallelshielding films 1308 are disposed around conductor set 1304. Aconformable adhesive layer 1310 is disposed between shielding films 1308and bonds shielding films 1308 to each other on both sides of conductorset 1304. Insulated conductors 1306 are arranged generally in a singleplane and effectively in a twinaxial or differential pair cablearrangement. Shielded electrical cable 1302 further includes a pluralityof ground conductors 1312 positioned between shielding films 1308. Twoof the ground conductors 1312 are included in conductor set 1304, andtwo of the ground conductors 1312 are spaced apart from conductor set1304.

Referring to FIG. 8c , shielded electrical cable 1402 includes a singleconductor set 1404. Conductor set 1404 includes two substantiallyparallel longitudinal insulated conductors 1406. Two generally parallelshielding films 1408 are disposed around conductor set 1404. Aconformable adhesive layer 1410 is disposed between shielding films 1408and bonds shielding films 1408 to each other on both sides of conductorset 1404. Insulated conductors 1406 are arranged generally in a singleplane and effectively in a twinaxial or differential pair cablearrangement. Shielded electrical cable 1402 further includes a pluralityof ground conductors 1412 positioned between shielding films 1408. Allof the ground conductors 1412 are included in conductor set 1404. Two ofthe ground conductors 1412 and insulated conductors 1406 are arrangedgenerally in a single plane.

FIGS. 9a-9b illustrate an exemplary embodiment of an electrical assemblyaccording to an aspect of the present invention terminated to a printedcircuit board. Electrical assembly 1500 includes a shielded electricalcable 1502 and an electrically conductive cable clip 1522. Shieldedelectrical cable 1502 includes a plurality of spaced apart conductorsets 1504 arranged generally in a single plane. Each conductor setincludes two substantially parallel longitudinal insulated conductors1506. Two generally parallel shielding films 1508 are disposed aroundconductor sets 1504. A conformable adhesive layer 1510 is disposedbetween shielding films 1508 and bonds shielding films 1508 to eachother on both sides of each conductor set 1504. Cable clip 1522 isclamped or otherwise attached to an end portion of shielded electricalcable 1502 such that at least one of shielding films 1508 electricallycontacts cable clip 1522. Cable clip 1522 is configured for terminationto a ground reference, such as, e.g., contact element 1516 on printedcircuit board 1514, to establish a ground connection between shieldedelectrical cable 1502 and the ground reference. Cable clip may beterminated to the ground reference using any suitable method, includingsoldering, welding, crimping, mechanical clamping, and adhesivelybonding, to name a few. When terminated, cable clip 1522 may facilitatetermination of the end portions of the conductors of insulatedconductors 1506 of shielded electrical cable 1502 to contact elements ofa termination point, such as, e.g., contact elements 16 on printedcircuit board 14. Shielded electrical cable 1502 may include one or moreground conductors as described herein that may electrically contactcable clip 1522 in addition to or instead of at least one of shieldingfilms 1508.

FIGS. 10a-10g illustrate an exemplary method of making a shieldedelectrical cable according to an aspect of the present invention.Specifically, FIGS. 10a-10g illustrate an exemplary method of makingshielded electrical cable 2 illustrated in FIG. 1.

In the step illustrated in FIG. 10a , insulated conductors 6 are formedusing any suitable method, such as, e.g., extrusion. Insulatedconductors 6 may be formed of any suitable length. Insulated conductors6 may then be provided as such or cut to a desired length. Groundconductors 12 may be formed and provided in a similar fashion (notshown). In the step illustrated in FIG. 10b , shielding films 8 areformed. A single layer or multilayer web may be formed using anysuitable method, such as, e.g., continuous wide web processing.Shielding films 8 may be formed of any suitable length. Shielding films8 may then be provided as such or cut to a desired length and/or width.Shielding films 8 may be pre-formed to have transverse partial folds toincrease flexibility in the longitudinal direction. As illustrated inFIG. 10b , shielding films 8 include conformable adhesive layer 10,which may be formed on shielding films 8 using any suitable method, suchas, e.g., laminating or sputtering. In the step illustrated in FIG. 10c, a plurality of insulated conductors 6, ground conductors 12, andshielding films 8 are provided. A forming tool 24 is provided. Formingtool 24 includes a pair of forming rolls 26 a, 26 b having a shapecorresponding to a cross-sectional shape of shielded electrical cable 2and include a bite 28. Insulated conductors 6, ground conductors 12, andshielding films 8 are arranged according to the configuration ofshielded electrical cable 2, and positioned in proximity to formingrolls 26 a, 26 b, after which they are concurrently fed into bite 28 offorming rolls 26 a, 26 b and disposed between forming rolls 26 a, 26 b.Forming tool 24 forms shielding films 8 around conductor sets 4 andground conductor 12 and bonds shielding films 8 to each other on bothsides of each conductor set 4 and ground conductors 12. Heat may beapplied to facilitate bonding. Although in this embodiment, formingshielding films 8 around conductor sets 4 and ground conductor 12 andbonding shielding films 8 to each other on both sides of each conductorset 4 and ground conductors 12 occur in a single operation, in otherembodiments, these steps may occur in separate operations. FIG. 10dillustrates shielded electrical cable 2 as it is formed by forming tool24. In the step illustrated in FIG. 10e , longitudinal splits 18 areformed between conductor sets 4. Splits 18 may be formed in shieldedelectrical cable 2 using any suitable method, such as, e.g., lasercutting or punching. In the step illustrated in FIG. 10f , shieldingfilms 8 of shielded electrical cable 2 are folded and an outerconductive shield 30 is provided around the folded shielding films 8using any suitable method. In the step illustrated in FIG. 10g , anouter jacket 32 is provided around outer conductive shield 30 using anysuitable method, such as, e.g., extrusion. In other embodiments, outerconductive shield 30 may be omitted and outer jacket 32 may be providedaround the folded shielding films 8.

FIGS. 11a-11c illustrate a detail of an exemplary method of making ashielded electrical cable according to an aspect of the presentinvention. FIGS. 11a-11c are specifically intended to illustrate anexample of the conforming of conformable adhesive layers during theforming and bonding of shielding films.

In the step illustrated in FIG. 11a , an insulated conductor 1606, aground conductor 1612 spaced apart from insulated conductor 1606, andtwo shielding films 1608 are provided. Shielding films 1608 each includea conformable adhesive layer 1610. In the steps illustrated in FIGS.11b-11c , shielding films 1608 are formed around insulated conductor1606 and ground conductor 1612 and bonded to each other. Initially, asillustrated in FIG. 11b , conformable adhesive layers 1610 still havetheir original thickness. As the forming and bonding of shielding films1608 proceeds, conformable adhesive layers 1610 conform to achievedesired mechanical and electrical performance characteristics ofshielded electrical cable 1602. Specifically, as illustrated in FIG. 11c, conformable adhesive layers 1610 conform to be thinner betweenshielding films 1608 on both sides of insulated conductor 1606 andground conductor 1612; a portion of conformable adhesive layers 1610displaces away from these areas. Further, conformable adhesive layers1610 conform to be thicker in areas immediately adjacent insulatedconductor 1606 and ground conductor 1612, and substantially conform toinsulated conductor 1606 and ground conductor 1612; a portion ofconformable adhesive layers 1610 displaces into these areas. Further,conformable adhesive layers 1610 conform to effectively be removedbetween shielding films 1608 and ground conductor 1612; conformableadhesive layers 1610 displace away from these areas such that groundconductor 1612 electrically contacts shielding films 1608.

In certain exemplary embodiments, the shielded electrical cableaccording to an aspect of the present invention includes a transitionportion positioned on one or both sides of the conductor set. Thistransition portion is configured to provide high manufacturability andstrain and stress relief of the shielded electrical cable. Maintainingthis transition portion at a substantially constant configuration(including aspects such as, e.g., size, shape, and content) along thelength of the shielded electrical cable facilitates the shieldedelectrical cable to have substantially uniform electrical properties,such as, e.g., impedance, skew, insertion loss, reflection, modeconversion, eye opening, and jitter. Additionally, in certainembodiments, such as, e.g., embodiments wherein the conductor setincludes two substantially parallel longitudinal insulated conductorsarranged generally in a single plane and effectively in a twinaxial ordifferential pair cable arrangement, maintaining this transition portionat a substantially constant configuration along the length of theshielded electrical cable beneficially provides substantially the sameelectromagnetic field deviation from an ideal concentric case for bothconductors in the conductor set. Thus, careful control of theconfiguration of this transition portion along the length of theshielded electrical cable contributes to the electrical performance ofthe cable. FIGS. 12a-14b illustrate various exemplary embodiments of ashielded electrical cable according to aspects of the present inventionthat include a transition portion disposed on one or both sides of theconductor set.

Referring now to FIGS. 12a-12b , shielded electrical cable 1702 includesa single conductor set 1704. Conductor set 1704 includes a singlelongitudinal insulated conductor 1706. Two generally parallel shieldingfilms 1708 are disposed around conductor set 1704. An optionalconformable adhesive layer 1710 is disposed between shielding films 1708and bonds shielding films 1708 to each other on both sides of conductorset 1704. Insulated conductor 1706 is effectively arranged in a coaxialor single ended cable arrangement. Shielding films 1708 include aconductive layer 1708 a and a non-conductive polymeric layer 1708 b.Conductive layer 1708 a faces insulated conductors 1706. Thisconfiguration of shielding films 1708 is similar to the configuration ofshielding films 908 shown in FIG. 7b . Alternatively, the configurationof shielding films 1708 may be similar to the configuration of shieldingfilms 808 shown in FIG. 7a , shielding films 1008 shown in FIG. 7c , orshielding films 1108 shown in FIG. 7d , for example. Shielding films1708 include a concentric portion 1708′ substantially concentric withconductor 1706 and parallel portions 1708″ wherein shielding films 1708are substantially parallel. In other embodiments, shielding films 1708may include a single parallel portion 1708″. Shielded electrical cable1702 further includes transition portions 1734 positioned on both sidesof conductor set 1704. In other embodiments, shielded electrical cable1702 may include a transition portion 1734 positioned on only one sideof conductor set 1704. Transition portions 1734 are defined by shieldingfilms 1708 and conductor set 1704 and provide a gradual transitionbetween concentric portion 1708′ and parallel portion 1708″ of shieldingfilms 1708. As opposed to a sharp transition, such as, e.g., aright-angle transition or a transition point (as opposed to a transitionportion), a gradual transition, such as, e.g., a substantially sigmoidaltransition, provides strain and stress relief for shielding films 1708in transition portions 1734 and prevents damage to shielding films 1708when shielded electrical cable 1702 is in use, e.g., when laterally oraxially bending shielded electrical cable 1702. This damage may include,e.g., fractures in conductive layer 1708 a and/or debonding betweenconductive layer 1708 a and non-conductive polymeric layer 1708 b. Inaddition, a gradual transition prevents damage to shielding films 1708in manufacturing of shielded electrical cable 1702, which may include,e.g., cracking or shearing of conductive layer 1708 a and/ornon-conductive polymeric layer 1708 b.

The configuration of shielded electrical cables according aspects of thepresent invention including a transition portion on one or both sides ofthe conductor set represents a departure from conventional cableconfigurations, such as, e.g., an ideal coaxial cable, wherein a shieldis generally continuously disposed around a single insulated conductor,or an ideal twinaxial cable, wherein a shield is generally continuouslydisposed around a pair of insulated conductors. Although these idealcable configurations provide ideal electromagnetic profiles, theseprofiles are not necessary to achieve acceptable electrical properties.In the shielded electrical cables according to aspects of the presentinvention, acceptable electrical properties can be achieved byminimizing the electrical impact of the transition portion, e.g., byminimizing the size of the transition portion and carefully controllingthe configuration of the transition portion along the length of theshielded electrical cable. Minimizing the size of the transition portionminimizes the capacitance deviation and minimizes the required spacebetween multiple conductor sets, thereby reducing the conductor setpitch and/or increasing the electrical isolation between conductor sets.Careful control of the configuration of the transition portion along thelength of the shielded electrical cable contributes to obtainingpredictable electrical behavior and consistency, which is important forhigh speed transmission lines so that electrical data can be reliablytransmitted, and becomes more important when the size of the transitionportion cannot be minimized. An electrical characteristic that is oftenconsidered is the characteristic impedance of the transmission line. Anyimpedance changes along the length of a transmission line may causepower to be reflected back to the source instead of being transmitted tothe target. Ideally, the transmission line will have no impedancevariation along its length, but, depending on the intended application,variations up to 5-10% may be acceptable. Another electricalcharacteristic that is often considered in twinaxial cables(differentially driven) is skew or unequal transmission speeds of twotransmission lines of a pair along at least a portion of their length.Skew produces conversion of the differential signal to a common modesignal that can be reflected back to the source, reduces the transmittedsignal strength, creates electromagnetic radiation, and dramaticallyincreases the bit error rate, in particular jitter. Ideally, a pair oftransmission lines will have no skew, but, depending on the intendedapplication, a differential S-parameter SCD21 or SCD12 value(representing the differential-to common mode conversion from one end ofthe transmission line to the other) of less than −25 to −30 dB up to afrequency of interest, such as, e.g., 6 GHz, may be acceptable.Alternatively, skew can be measured in the time domain and compared to arequired specification. Depending on the intended application, values ofless than about 20 picoseconds/meter (ps/m) and preferably less thanabout 10 ps/m may be acceptable.

Referring back to FIGS. 12a-12b , in part to help achieve acceptableelectrical properties, transition portions 1734 of shielded electricalcable 1702 may each include a cross-sectional area 1734 a that issmaller than a cross-sectional area 1706 a of conductor 1706. As bestshown in FIG. 12b , cross-sectional area 1734 a of transition portion1734 is defined by transition points 1734′, where shielding films 1708deviate from being substantially concentric with insulated conductor1706, and transition points 1734″, where shielding films 1708 deviatefrom being substantially parallel. In addition, each cross-sectionalarea 1734 a may include a void portion 1734 b. Void portions 1734 b maybe substantially the same. Further, conformable adhesive layer 1710 mayhave a thickness T_(ac) in concentric portion 1708′, and a thickness intransition portion 1734 that is greater than thickness T_(ac) inconcentric portion 1708′. Similarly, conformable adhesive layer 1710 mayhave a thickness T_(ap) in parallel portion 1708″, and a thickness intransition portion 1734 that is greater than thickness T_(ap) inparallel portion 1708″. Conformable adhesive layer 1710 may represent atleast 25% of cross-sectional area 1734 a. The presence of conformableadhesive layer 1710 in cross-sectional area 1734 a, in particular at athickness that is greater than thickness T_(ac) or thickness T_(ap),contributes to the strength of transition portion 1734. Careful controlof the manufacturing process and the material characteristics of thevarious elements of shielded electrical cable 1702 may reduce variationsin void portion 1734 b and the thickness of conformable adhesive layer1710 in transition portion 1734, which may in turn reduce variations inthe capacitance of cross-sectional area 1734 a. Shielded electricalcable 1702 may include a transition portion 1734 positioned on one orboth sides of conductor set 1704 that includes a cross-sectional area1734 a that is substantially equal to or smaller than a cross-sectionalarea 1706 a of conductor 1706. Shielded electrical cable 1702 mayinclude a transition portion 1734 positioned on one or both sides ofconductor set 1704 that includes a cross-sectional area 1734 a that issubstantially the same along the length of conductor 1706. For example,cross-sectional area 1734 a may vary less than 50% over a length of 1 m.Shielded electrical cable 1702 may include transition portions 1734positioned on both sides of conductor set 1704 that each include across-sectional area 1734 a, wherein the sum of cross-sectional areas1734 a is substantially the same along the length of conductor 1706. Forexample, the sum of cross-sectional areas 1734 a may vary less than 50%over a length of 1 m. Shielded electrical cable 1702 may includestransition portions 1734 positioned on both sides of conductor set 1704that each include a cross-sectional area 1734 a, wherein thecross-sectional areas 1734 a are substantially the same. Shieldedelectrical cable 1702 may include transition portions 1734 positioned onboth sides of conductor set 1704, wherein the transition portions 1734are substantially identical. Insulated conductor 1706 has an insulationthickness T_(i), and transition portion 1734 may have a lateral lengthL_(t) that is less than insulation thickness T_(i). Insulated conductor1706 has a diameter D_(c), and transition portion 1734 may have alateral length L_(t) that is less than diameter D_(c). The variousconfigurations described above may provide a characteristic impedancethat remains within a desired range, such as, e.g., within 5-10% of atarget impedance value, such as, e.g., 50 Ohms, over a given length,such as, e.g., 1 m.

Factors that control the configuration of transition portion 1734 alongthe length of shielded electrical cable 1702 include the manufacturingprocess, the thickness of conductive layers 1708 a and non-conductivepolymeric layers 1708 b, conformable adhesive layer 1710, and the bondstrength between insulated conductor 1706 and shielding films 1708, toname a few.

In one aspect, conductor set 1704, shielding films 1708, and transitionportion 1734 are cooperatively configured in an impedance controllingrelationship. An impedance controlling relationship means that conductorset 1704, shielding films 1708, and transition portion 1734 arecooperatively configured to control the characteristic impedance of theshielded electrical cable.

FIGS. 13a-13b illustrate two other exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention includingtwo insulated conductors. Referring to FIG. 13a , shielded electricalcable 1802 includes a single conductor set 1804 including twosubstantially parallel longitudinal individually insulated conductors1806. Two generally parallel shielding films 1808 are disposed aroundconductor set 1804. An optional conformable adhesive layer 1810 isdisposed between shielding films 1808 and bonds shielding films 1808 toeach other on both sides of conductor set 1804. Insulated conductors1806 are arranged generally in a single plane and effectively in atwinaxial or differential pair cable arrangement. Shielding films 1808include a conductive layer 1808 a and a non-conductive polymeric layer1808 b. Conductive layer 1808 a faces insulated conductors 1806.Shielding films 1808 include concentric portions 1808′ substantiallyconcentric with corresponding conductors 1806 and parallel portions1808″ wherein shielding films 1808 are substantially parallel. Shieldedelectrical cable 1802 includes transition portions 1834 positioned onboth sides of conductor set 1804 that each include a cross-sectionalarea 1834 a, wherein the sum of cross-sectional areas 1834 a issubstantially the same along the length of conductors 1806. For example,the sum of cross-sectional areas 1834 a may vary less than 50% over alength of 1 m. In addition, cross-sectional areas 1834 a aresubstantially the same and transition portions 1834 are substantiallyidentical. This configuration of transition portions 1834 may provide acharacteristic impedance for each conductor 1806 (single-ended) and adifferential impedance that both remain within a desired range, such as,e.g., within 5-10% of a target impedance value over a given length, suchas, e.g., 1 m. In addition, this configuration of transition portions1834 may minimize skew of the two conductors 1806 along at least aportion of their length. Referring to FIG. 13b , shielded electricalcable 1902 is similar to shielded electrical cable 1802. Whereasshielded electrical cable 1802 has individually insulated conductors1806, shielded electrical cable 1902 has jointly insulated conductors1906. Nonetheless, transition portions 1934 are identical to transitionportions 1834 and provide the same benefits to shielded electrical cable1902.

FIGS. 14a-14b illustrate two other exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention includingtwo insulated conductors. These exemplary embodiments are intended toillustrate variations in position and configuration of the transitionportions. Shielded electrical cables 2002 (FIG. 14a ) and 2102 (FIG. 14b) are similar to shielded electrical cable 1802. Whereas in shieldedelectrical cable 1802, parallel portions 1808″ of shielding films 1808and insulated conductors 1806 are arranged generally in a single plane,in shielded electrical cables 2002 and 2102, parallel portions 2008″ and2108″ of shielding films 2008 and 2108 and insulated conductors 2006 and2106 are arranged in different planes. As a result, transition portions2034 and 2134 have a different position and configuration. For reasonsincluding that transition portions 2034 and 2134 are positionedsubstantially symmetrically with respect to corresponding insulatedconductors 2006 and 2106 and that the configuration of transitionportions 2034 and 2134 is carefully controlled along the length ofshielded electrical cables 2002 and 2102, shielded electrical cables2002 and 2102 are configured to still provide acceptable electricalproperties.

In further exemplary embodiments, shielded electrical cables accordingto aspects of the present invention include a plurality of spaced apartconductor sets arranged generally in a single plane. Each conductor setincludes one or more substantially parallel longitudinal insulatedconductors. Two generally parallel shielding films are disposed aroundthe conductor sets and include a plurality of concentric portionssubstantially concentric with at least one of the conductors and aplurality of parallel portions wherein the shielding films aresubstantially parallel. A plurality of transition portions defined bythe shielding films and the conductor sets provide a gradual transitionbetween the concentric portions and the parallel portions of theshielding films. The transition portions may be positioned on both sidesof each conductor set. For example, the shielded electrical cable mayinclude a combination of one or more conductor sets 1704, whereininsulated conductor 1706 is effectively arranged in a coaxial or singleended cable arrangement, and one or more conductor sets 1804, whereininsulated conductors 1806 are effectively arranged in a twinaxial ordifferential pair cable arrangement. The conductor sets, shielding filmsand transition portions may be cooperatively configured in an impedancecontrolling relationship.

FIGS. 15a-15c , 18 and 19 illustrate several other exemplary embodimentsof a shielded electrical cable according to aspects of the presentinvention. FIGS. 16a-16g, 17a-17b and 20a-20f illustrate severalexemplary embodiments of a parallel portion of a shielded electricalcable according to aspects of the present invention. FIGS. 15a-20f arespecifically intended to illustrate examples of a parallel portion thatis configured to electrically isolate a conductor set of the shieldedelectrical cable. The conductor set may be electrically isolated from anadjacent conductor set (e.g., to minimize crosstalk between adjacentconductor sets, FIGS. 15a-15c and 16a-16g ) or from the externalenvironment of the shielded electrical cable (e.g., to minimizeelectromagnetic radiation escape from the shielded electrical cable andminimize electromagnetic interference from external sources, FIGS. 19and 20 a-20 f). In both cases, the parallel portion may include variousmechanical structures to realize the electrical isolation. Examplesinclude close proximity of the shielding films, high dielectric constantmaterial between the shielding films, ground conductors that make director indirect electrical contact with at least one of the shielding films,extended distance between adjacent conductor sets, physical breaksbetween adjacent conductor sets, intermittent contact of the shieldingfilms to each other directly either longitudinally, transversely, orboth, and conductive adhesive, to name a few. In one aspect, a parallelportion of the shielding films is defined as a portion of the shieldingfilms that is not covering a conductor set.

In FIG. 15a , shielded electrical cable 2202 includes two conductor sets2204, each including two substantially parallel longitudinal insulatedconductors 2206, and two generally parallel shielding films 2208disposed around conductor sets 2204. Shielding films 2208 includeparallel portions 2208″ wherein shielding films 2208 are substantiallyparallel. Parallel portions 2208″ positioned in between conductor sets2204 are configured to electrically isolate conductor sets 2204 fromeach other. In shielded electrical cable 2202, parallel portions 2208″of shielding films 2208 and insulated conductors 2206 are arrangedgenerally in a single plane.

In FIG. 15b , shielded electrical cable 2302 includes two conductor sets2304, each including one longitudinal insulated conductor 2306, and twogenerally parallel shielding films 2308 disposed around conductor sets2304. Shielding films 2308 include parallel portions 2308″ whereinshielding films 2308 are substantially parallel. Parallel portions 2308″positioned in between conductor sets 2304 are configured to electricallyisolate conductor sets 2304 from each other. In shielded electricalcable 2302, parallel portions 2308″ of shielding films 2308 andinsulated conductors 2306 are arranged generally in a single plane.

In FIG. 15c , shielded electrical cable 2402 includes two conductor sets2404, each including two substantially parallel longitudinal insulatedconductors 2406, and two generally parallel shielding films 2408disposed around conductor sets 2404. Shielding films 2408 includeparallel portions 2408″ wherein shielding films 2408 are substantiallyparallel. Parallel portions 2408″ positioned in between conductor sets2404 are configured to electrically isolate conductor sets 2404 fromeach other. In shielded electrical cable 2402, parallel portions 2408″of shielding films 2408 and insulated conductors 2406 are arranged indifferent planes.

In FIG. 16a , shielded electrical cable 2502 includes a parallel portion2508″ wherein shielding films 2508 are spaced apart. Spacing apartshielding films 2508, i.e., not having shielding films 2508 make directelectrical contact continuously along their seam, increases the strengthof parallel portion 2508″. This is an advantage over shielded electricalcables wherein relatively thin and fragile shielding films may fractureor crack during manufacturing if forced to make direct electricalcontact continuously along their seam. Spacing apart shielding films2508 may permit crosstalk between adjacent conductor sets if effectivemeans are not used to reduce the crosstalk potential. Generally, theelectrical and magnetic fields must be contained to the general area ofthe conductor sets and not permitted to impinge on an adjacent conductorset. In the embodiment illustrated in FIG. 16a , this is achieved byproviding a low characteristic impedance between shielding films 2508.This may be accomplished by spacing apart shielding films 2508 at closeproximity. In one embodiment, shielding films 2508 are spaced apart byless than about 0.13 mm in at least one location of parallel portion2508″. The resulting characteristic impedance between shielding films2508 may be less than about 15 Ohms, and the resulting crosstalk betweenadjacent conductor sets may be less than about −25 dB. In oneembodiment, parallel portion 2508″ has a minimum thickness of less thanabout 0.13 mm. In one embodiment, shielding films 2508 are spaced apartby a separation medium. The separation medium may include conformableadhesive layer 2510. In one embodiment, the separation medium has adielectric constant of at least 1.5. A high dielectric constantdecreases the characteristic impedance between shielding films 2508,thereby decreasing the crosstalk (increasing the electrical isolation)between adjacent conductor sets. Shielding films 2508 may make directelectrical contact with each other in at least one location of parallelportion 2508″. Shielding films 2508 may be forced together in selectivelocations as suitable for the intended application such that conformableadhesive layer 2510 conforms around these locations. This can be done,e.g., with a patterned tool making intermittent pinch contact betweenshielding films 2508 in these locations. These locations may bepatterned longitudinally or transversely. In one embodiment, theseparation medium may be electrically conductive to enable directelectrical contact between shielding films 2508.

In FIG. 16b , shielded electrical cable 2602 includes a parallel portion2608″ including a longitudinal ground conductor 2612 disposed betweenshielding films 2608. Ground conductor 2612 makes indirect electricalcontact with both shielding films 2608. Ground conductor 2612 has a lowbut non-zero impedance with respect to shielding films 2608. In otherembodiments, ground conductor 2612 may make direct or indirectelectrical contact with at least one of the shielding films 2608 in atleast one location of parallel portion 2608″. In one embodiment,shielded electrical cable 2602 includes a conformable adhesive layer2610 disposed between shielding films 2608 and configured to providecontrolled separation of at least one of shielding films 2608 and groundconductor 2612. In one aspect, this means that conformable adhesivelayer 2610 has a non-uniform thickness that allows ground conductor 2612to make direct or indirect electrical contact with at least one ofshielding films 2608 in selective locations as suitable for the intendedapplication. In one embodiment, ground conductor 2612 may includesurface asperities or a deformable wire, such as, e.g., a stranded wire,to provide this controlled electrical contact between ground conductor2612 and at least one of shielding films 2608.

In FIG. 16c , shielded electrical cable 2702 includes a parallel portion2708″ including a longitudinal ground conductor 2712 disposed betweenshielding films 2708. Ground conductor 2712 makes direct electricalcontact with both shielding films 2708.

In FIG. 16d , shielded electrical cable 2802 includes a parallel portion2808″ wherein shielding films 2808 make direct electrical contact witheach other by any suitable means, such as, e.g., conductive element2844. Conductive element 2844 may include a conductive plated via orchannel, a conductive filled via or channel, or a conductive adhesive,to name a few.

In FIG. 16e , shielded electrical cable 2902 includes a parallel portion2908″ including an opening 2936 in at least one location of parallelportion 2908″. In other words, parallel portion 2908″ is discontinuous.Opening 2936 may include a hole, a perforation, a slit, and any othersuitable element. Opening 2936 provides at least some level of physicalseparation, which contributes to the electrical isolation performance ofparallel portion 2908″ and increases at least the lateral flexibility ofshielded electrical cable 2902. This separation may be discontinuousalong the length of parallel portion 2908″, and may be discontinuousacross the width of parallel portion 2908″.

In FIG. 16f , shielded electrical cable 3002 includes a parallel portion3008″ wherein at least one of shielding films 3008 includes a break 3038in at least one location of parallel portion 3008″. In other words, atleast one of shielding films 3008 is discontinuous. Break 3038 mayinclude a hole, a perforation, a slit, and any other suitable element.Break 3038 provides at least some level of physical separation, whichcontributes to the electrical isolation performance of parallel portion3008″ and increases at least the lateral flexibility of shieldedelectrical cable 3002. This separation may be discontinuous orcontinuous along the length of parallel portion 3008″, and may bediscontinuous across the width of parallel portion 3008″.

In FIG. 16g , shielded electrical cable 3102 includes a parallel portion3108″ that is piecewise planar in a folded configuration. All otherthings being equal, a piecewise planar parallel portion has a greateractual width than a planar parallel portion having the same projectedwidth. If the actual width of a parallel portion is much greater thanthe spacing between the shielding films, a low characteristic impedanceresults, which contributes to the electrical isolation performance ofthe parallel portion. In one embodiment, a characteristic impedance ofless than 5 to 10 Ohms results in good electrical isolation. In oneembodiment, parallel portion 3108″ of shielded electrical cable 3102 hasan actual width to minimum spacing ratio of at least 5. In oneembodiment, parallel portion 3108″ is pre-bent and thereby increases atleast the lateral flexibility of shielded electrical cable 3102.Parallel portion 3108″ may be piecewise planar in any other suitableconfiguration.

Referring now to FIGS. 17a-17b , another exemplary embodiment of aparallel portion of a shielded electrical cable according to an aspectof the present invention is illustrated. Shielded electrical cable 3202includes two generally parallel shielding films 3208 include a parallelportion 3208″ wherein shielding films 3208 are substantially parallel.Shielding films 3208 include a non-conductive polymeric layer 3208 b, aconductive layer 3208 a disposed on non-conductive polymeric layer 3208b, and a stop layer 3208 d disposed on conductive layer 3208 a. Aconformable adhesive layer 3210 is disposed on stop layer 3208 d.Parallel portion 3208″ includes a longitudinal ground conductor 3212disposed between shielding films 3208. Ground conductor 3212 makesindirect electrical contact with conductive layers 3208 a of shieldingfilms 3208. This indirect electrical contact is enabled by a controlledseparation of conductive layer 3208 a and ground conductor 3212 providedby stop layer 3208 d. In one embodiment, stop layer 3208 d is anon-conductive polymeric layer. As shown in FIGS. 17a-17b , an externalpressure (FIG. 17a ) is used to press conductive layers 3208 a togetherand force conformable adhesive layers 3210 to conform around groundconductor 3212 (FIG. 17b ). Because stop layer 3208 d does not conformat least under the same conditions, it prevents direct electricalcontact between ground conductor 3212 and conductive layer 3208 a ofshielding films 3208. The thickness and dielectric properties of stoplayer 3208 d may be selected to achieve a target characteristicimpedance. In one embodiment, a characteristic impedance of less than 5to 10 Ohms results in good electrical isolation.

FIG. 18 illustrates another exemplary embodiment of a shieldedelectrical cable according to an aspect of the present invention.Shielded electrical cable 3302 includes two generally parallel shieldingfilms 3308 disposed around spaced apart conductor sets 3304. Shieldingfilms 3308 include parallel portions 3308″ wherein shielding films 3308are substantially parallel. Parallel portions 3308″ are configured to belaterally bent at an angle α of at least 30°. This lateral flexibilityof parallel portions 3308″ enables shielded electrical cable 3302 to befolded in any suitable configuration, such as, e.g., a configurationthat can be used in a round cable (see, e.g., FIG. 10g ). In oneembodiment, the lateral flexibility of parallel portions 3308″ isenabled by shielding films 3308 including two or more relatively thinindividual layers. To warrant the integrity of these individual layersin particular under bending conditions, it is preferred that the bondsbetween them remain intact. In one embodiment, parallel portions 3308″have a minimum thickness of less than about 0.13 mm, and the bondstrength between individual layers is at least 17.86 g/mm (1 lbs/inch)after thermal exposures during processing or use.

In one aspect, it is beneficial to the electrical performance of ashielded electrical cable according to aspect of the present inventionfor the parallel portions to have approximately the same size and shapeon both sides of a conductor set. Any dimensional changes or imbalancesmay produce imbalances in capacitance and inductance along the length ofthe parallel portion. This in turn may cause impedance differences alongthe length of the parallel portion and impedance imbalances betweenadjacent conductor sets. At least for these reasons, control of thespacing between the shielding films may be desired. In one embodiment,the shielding films on both sides of a conductor set are spaced apartwithin about 0.05 mm of each other.

In FIG. 19, shielded electrical cable 3402 includes two conductor sets3404, each including two substantially parallel longitudinal insulatedconductors 3406, and two generally parallel shielding films 3408disposed around conductor sets 3404. Shielding films 3408 includeparallel portions 3408″ wherein shielding films 3408 are substantiallyparallel. Parallel portions 3408″ positioned at or near an edge ofshielded electrical cable 3402 are configured to electrically isolateconductor sets 3404 from the external environment. In shieldedelectrical cable 3402, parallel portions 3408″ of shielding films 3408and insulated conductors 3406 are arranged generally in a single plane.

In FIG. 20a , shielded electrical cable 3502 includes a parallel portion3508″ wherein shielding films 3508 are spaced apart. Parallel portion3508″ is similar to parallel portion 2508″ described above andillustrated in FIG. 16a . Whereas parallel portion 2508″ is positionedin between conductor sets, parallel portion 3508″ is positioned at ornear an edge of shielded electrical cable 3502.

In FIG. 20b , shielded electrical cable 3602 includes a parallel portion3608″ including a longitudinal ground conductor 3612 disposed betweenshielding films 3608. Parallel portion 3608″ is similar to parallelportion 2608″ described above and illustrated in FIG. 16b . Whereasparallel portion 2608″ is positioned in between conductor sets, parallelportion 3608″ is positioned at or near an edge of shielded electricalcable 3602.

In FIG. 20c , shielded electrical cable 3702 includes a parallel portion3708″ including a longitudinal ground conductor 3712 disposed betweenshielding films 3708. Parallel portion 3708″ is similar to parallelportion 2708″ described above and illustrated in FIG. 16c . Whereasparallel portion 2708″ is positioned in between conductor sets, parallelportion 3708″ is positioned at or near an edge of shielded electricalcable 3702.

In FIG. 20d , shielded electrical cable 3802 includes a parallel portion3808″ wherein shielding films 3808 make direct electrical contact witheach other by any suitable means, such as, e.g., conductive element3844. Conductive element 3844 may include a conductive plated via orchannel, a conductive filled via or channel, or a conductive adhesive,to name a few. Parallel portion 3808″ is similar to parallel portion2808″ described above and illustrated in FIG. 16d . Whereas parallelportion 2808″ is positioned in between conductor sets, parallel portion3808″ is positioned at or near an edge of shielded electrical cable3802.

In FIG. 20e , shielded electrical cable 3902 includes a parallel portion3908″ that is piecewise planar in a folded configuration. Parallelportion 3908″ is similar to parallel portion 3108″ described above andillustrated in FIG. 16g . Whereas parallel portion 3108″ is positionedin between conductor sets, parallel portion 3908″ is positioned at ornear an edge of shielded electrical cable 3902.

In FIG. 20f , shielded electrical cable 4002 includes a parallel portion4008″ that is piecewise planar in a curved configuration and positionedat or near an edge of shielded electrical cable 4002.

A shielded electrical cable according to an aspect of the presentinvention may include at least one longitudinal ground conductor, anelectrical article extending in substantially the same direction as theground conductor, and two generally parallel shielding films disposedaround the ground conductor and the electrical article. In thisconfiguration, the shielding films and ground conductor are configuredto electrically isolate the electrical article. The ground conductor mayextend beyond at least one of the ends of the shielding films, e.g., fortermination of the shielding films to any suitable individual contactelement of any suitable termination point, such as, e.g., a contactelement on a printed circuit board or an electrical contact of anelectrical connector. Beneficially, only a limited number of groundconductors is needed for a cable construction, and can, along with theshielding films, complete an electromagnetic enclosure of the electricalarticle. The electrical article may include at least one longitudinalconductor, at least one conductor set including one or moresubstantially parallel longitudinal insulated conductors, a flexibleprinted circuit, or any other suitable electrical article of whichelectrical isolation is desired. FIGS. 21a-21b illustrate two exemplaryembodiments of such shielded electrical cable configuration.

In FIG. 21a , shielded electrical cable 4102 includes two spaced apartsubstantially parallel longitudinal ground conductors 4112, anelectrical article 4140 positioned between and extending insubstantially the same direction as ground conductors 4112, and twogenerally parallel shielding films 4108 disposed around groundconductors 4112 and electrical article 4140. Electrical article 4140includes three conductor sets 4104. Each conductor set 4104 includes twosubstantially parallel longitudinal insulated conductors 4106. Groundconductors 4112 make indirect electrical contact with both shieldingfilms 4108. Ground conductors 4112 have a low but non-zero impedancewith respect to shielding films 4108. In other embodiments, groundconductors 4112 may make direct or indirect electrical contact with atleast one of the shielding films 4108 in at least one location ofshielding films 4108. In one embodiment, shielded electrical cable 4102includes a conformable adhesive layer 4110 disposed between shieldingfilms 4108 and bonding shielding films 4108 to each other on both sidesof ground conductors 4112 and electrical article 4140. Conformableadhesive layer 4110 is configured to provide controlled separation of atleast one of shielding films 4108 and ground conductors 4112. In oneaspect, this means that conformable adhesive layer 4110 has anon-uniform thickness that allows ground conductors 4112 to make director indirect electrical contact with at least one of shielding films 4108in selective locations as suitable for the intended application. In oneembodiment, ground conductors 4112 may include surface asperities or adeformable wire, such as, e.g., a stranded wire, to provide thiscontrolled electrical contact between ground conductors 4112 and atleast one of shielding films 4108. In one embodiment, shielding films4108 are spaced apart by a minimum spacing in at least one location ofshielding films 4108, and ground conductors 4112 have a thickness thatis greater than the minimum spacing. In one embodiment, shielding films4108 have a thickness of less than about 0.025 mm.

In FIG. 21b , shielded electrical cable 4202 includes two spaced apartsubstantially parallel longitudinal ground conductors 4212, anelectrical article 4240 positioned between and extending insubstantially the same direction as ground conductors 4212, and twogenerally parallel shielding films 4208 disposed around groundconductors 4212 and electrical article 4240. Shielded electrical cable4202 is similar to shielded electrical cable 4102 described above andillustrated in FIG. 21a . Whereas in shielded electrical cable 4102,electrical article 4140 includes three conductor sets 4104 eachincluding two substantially parallel longitudinal insulated conductors4106, in shielded electrical cable 4202, electrical article 4240includes a flexible printed circuit including three conductor sets 4242.

FIG. 22 illustrates the far end crosstalk (FEXT) isolation between twoadjacent conductor sets of a conventional electrical cable wherein theconductor sets are completely isolated, i.e., have no common ground(Sample 1), and between two adjacent conductor sets of shieldedelectrical cable 2202 illustrated in FIG. 15a wherein shielding films2208 are spaced apart by about 0.025 mm (Sample 2), both having a cablelength of about 3 m. The test method for creating this data is wellknown in the art. The data was generated using an Agilent 8720ES 50MHz-20 GHz S-Parameter Network Analyzer. It can be seen by comparing thefar end crosstalk plots that the conventional electrical cable andshielded electrical cable 2202 provide a similar far end crosstalkperformance. Specifically, it is generally accepted that a far endcrosstalk of less than about −35 dB is suitable for most applications.It can be easily seen from FIG. 22 that for the configuration tested,both the conventional electrical cable and shielded electrical cable2202 provide satisfactory electrical isolation performance. Thesatisfactory electrical isolation performance in combination with theincreased strength of the parallel portion due to the ability to spaceapart the shielding films is an advantage of a shielded electrical cableaccording to an aspect of the present invention over conventionalelectrical cables.

In exemplary embodiments described above, the shielded electrical cableincludes two generally parallel shielding films disposed around aconductor set or around a plurality of spaced apart conductor sets. Infurther embodiments, the shielded electrical cable may include a singleshielding film. Advantages of a shielded electrical cable including asingle shielding film, compared to a shielded electrical cable includingtwo shielding films, include a decrease in its material cost and anincrease in its mechanical flexibility, manufacturability, and ease ofstripping and termination. A single shielding film may provide anacceptable level of electromagnetic interference (EMI) isolation and mayreduce the proximity effect thereby decreasing signal attenuation. FIGS.23-29 d illustrate various exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention includinga single shielding film.

Referring now to FIG. 23, shielded electrical cable 4302 includes twospaced apart conductor sets 4304 and a single shielding film 4308. Eachconductor set 4304 includes a single longitudinal insulated conductor4306. Insulated conductors 4306 are arranged generally in a single planeand effectively in a coaxial or single ended cable arrangement.Shielding film 4308 includes parallel portions 4308″ extending from bothsides of each conductor set 4304. Parallel portions 4308″ cooperativelydefine a generally planar shielding film. Shielding film 4308 furtherincludes two cover portions 4308′″ each partially covering a conductorset 4304. Each cover portion 4308′″ includes a concentric portion 4308′substantially concentric with corresponding conductor 4306. Shieldingfilm 4308 includes a conductive layer 4308 a and a non-conductivepolymeric layer 4308 b. Conductive layer 4308 a faces insulatedconductors 4306. Shielded electrical cable 4302 further includes anoptional non-conductive carrier film 4346. Carrier film 4346 includesparallel portions 4346″ extending from both sides of each conductor set4304 and disposed opposite parallel portions 4308″ of shielding film4308. Carrier film 4346 further includes two cover portions 4346′″ eachpartially covering a conductor set 4304 opposite cover portion 4308′″ ofshielding film 4308. Each cover portion 4346′″ includes a concentricportion 4346′ substantially concentric with corresponding conductor4306. Carrier film 4346 may include any suitable polymeric material,including but not limited to polyester, polyimide, polyamide-imide,polytetrafluoroethylene, polypropylene, polyethylene, polyphenylenesulfide, polyethylene naphthalate, polycarbonate, silicone rubber,ethylene propylene diene rubber, polyurethane, acrylates, silicones,natural rubber, epoxies, and synthetic rubber adhesive. Carrier film4346 may include one or more additives and/or fillers to provideproperties suitable for the intended application. Carrier film 4346 maybe used to complete physical coverage of conductor sets 4304 and add tothe mechanical stability of shielded electrical cable 4302.

Referring to FIG. 24, shielded electrical cable 4402 is similar toshielded electrical cable 4302 described above and illustrated in FIG.23. Whereas shielded electrical cable 4302 includes conductor sets 4304each including a single longitudinal insulated conductor 4306, shieldedelectrical cable 4402 includes conductor sets 4404 including twosubstantially parallel longitudinal insulated conductors 4406. Insulatedconductors 4406 are arranged generally in a single plane and effectivelyin a twinaxial or differential pair cable arrangement.

Referring to FIG. 25, shielded electrical cable 4502 is similar toshielded electrical cable 4402 described above and illustrated in FIG.24. Whereas shielded electrical cable 4402 has individually insulatedconductors 4406, shielded electrical cable 4502 has jointly insulatedconductors 4506.

In one aspect, as can be seen in FIGS. 23-25, the shielding film isre-entrant between adjacent conductor sets. In other words, theshielding film includes a parallel portion that is disposed betweenadjacent conductor sets. This parallel portion is configured toelectrically isolate the adjacent conductor sets from each other. In oneaspect, the parallel portion eliminates the need for a ground conductorto be positioned between adjacent conductor sets, which simplifies thecable construction and increases the cable flexibility, among otherbenefits. In one embodiment, the parallel portion is positioned at adepth d (FIG. 23) that is greater than about one third of the diameterof the insulated conductors. In another embodiment, the parallel portionis positioned at a depth d that is greater than about one half of thediameter of the insulated conductors. In one aspect, depending on thespacing between adjacent conductor sets, the transmission distance, andthe signaling scheme (differential versus single-ended), this re-entrantconfiguration of the shielding film more than adequately electricallyisolates the conductor sets from each other.

The conductor sets and shielding film may be cooperatively configured inan impedance controlling relationship. In one aspect, this means thatthe partial coverage of the conductor sets by the shielding film isaccomplished with a desired consistency in geometry along the length ofthe shielded electrical cable such as to provide an acceptable impedancevariation as suitable for the intended application. In one embodiment,this impedance variation is less than 5 Ohms and preferably less than 3Ohms along a representative cable length, such as, e.g., 1 m. In anotheraspect, if the insulated conductors are arranged effectively in atwinaxial or differential pair cable arrangement, this means that thepartial coverage of the conductor sets by the shielding film isaccomplished with a desired consistency in geometry between theinsulated conductors of a pair such as to provide an acceptableimpedance variation as suitable for the intended application. In oneembodiment, this impedance variation is less than 2 Ohms and preferablyless than 0.5 Ohms along a representative cable length, such as, e.g., 1m.

FIGS. 26a-26d illustrate various exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention. FIGS.26a-26d are specifically intended to illustrate various examples ofpartial coverage of the conductor set by the shielding film. The amountof coverage by the shielding film varies between the embodiments. In theembodiment illustrated in FIG. 26a , the conductor set has the mostcoverage. In the embodiment illustrated in FIG. 26d , the conductor sethas the least coverage. In the embodiments illustrated in FIGS. 26a and26b , more than half of the periphery of the conductor set is covered bythe shielding film. In the embodiments illustrated in FIGS. 26c and 26d, less than half of the periphery of the conductor set is covered by theshielding film. A greater amount of coverage provides betterelectromagnetic interference (EMI) isolation and reduced signalattenuation (resulting from a reduction in the proximity effect).

Referring to FIG. 26a , shielded electrical cable 4602 includes aconductor set 4604 and a shielding film 4608. Conductor set 4604includes two longitudinal insulated conductors 4606. Shielding film 4608includes parallel portions 4608″ extending from both sides of conductorset 4604. Parallel portions 4608″ cooperatively define a generallyplanar shielding film. Shielding film 4608 further includes a coverportion 4608′″ partially covering conductor set 4604. Cover portion4608′″ includes concentric portions 4608′ substantially concentric withcorresponding conductor 4306. Shielded electrical cable 4602 furtherincludes an optional non-conductive carrier film 4646. Carrier film 4646includes parallel portions 4646″ extending from both sides of conductorset 4604 and disposed opposite parallel portions 4608″ of shielding film4608. Carrier film 4646 further includes a cover portion 4646′″partially covering conductor set 4604 opposite cover portion 4608′″ ofshielding film 4608. Cover portion 4608′″ of shielding film 4608 coversthe top side and the entire left and right sides of conductor set 4604.Cover portion 4646′″ of carrier film 4646 covers the bottom side ofconductor set 4604, completing the enclosure of conductor set 4604. Inthis embodiment, parallel portions 4646″ and cover portion 4646′″ ofcarrier film 4646 are substantially coplanar.

Referring to FIG. 26b , shielded electrical cable 4702 is similar toshielded electrical cable 4602 described above and illustrated in FIG.26a . However, in shielded electrical cable 4702, cover portion 4708′″of shielding film 4708 covers the top side and more than half of theleft and right sides of conductor set 4704. Cover portion 4746′″ ofcarrier film 4746 covers the bottom side and the remainder (less thanhalf) of the left and right sides of conductor set 4704, completing theenclosure of conductor set 4704. Cover portion 4746′″ of carrier film4746 includes concentric portions 4746′ substantially concentric withcorresponding conductor 4706.

Referring to FIG. 26c , shielded electrical cable 4802 is similar toshielded electrical cable 4602 described above and illustrated in FIG.26a . However, in shielded electrical cable 4802, cover portion 4808′″of shielding film 4808 covers the bottom side and less than half of theleft and right sides of conductor set 4804. Cover portion 4846′″ ofcarrier film 4846 covers the top side and the remainder (more than half)of the left and right sides of conductor set 4804, completing theenclosure of conductor set 4804.

Referring to FIG. 26d , shielded electrical cable 4902 is similar toshielded electrical cable 4602 described above and illustrated in FIG.26a . However, in shielded electrical cable 4902, cover portion 4908′″of shielding film 4908 covers the bottom side of conductor set 4904.Cover portion 4946′″ of carrier film 4946 covers the top side and theentire left and right sides of conductor set 4904, completing theenclosure of conductor set 4904. In this embodiment, parallel portions4908″ and cover portion 4908′″ of shielding film 4908 are substantiallycoplanar.

Similar to embodiments of the shielded electrical cable including twogenerally parallel shielding films disposed around a conductor set oraround a plurality of spaced apart conductor sets, embodiments of theshielded electrical cable including a single shielding film may includeat least one longitudinal ground conductor. In one aspect, this groundconductor facilitates electrical contact of the shielding film to anysuitable individual contact element of any suitable termination point,such as, e.g., a contact element on a printed circuit board or anelectrical contact of an electrical connector. The ground conductor mayextend beyond at least one of the ends of the shielding film tofacilitate this electrical contact. The ground conductor may make director indirect electrical contact with the shielding film in at least onelocation along its length, and may be placed in suitable locations ofthe shielded electrical cable.

FIG. 27 is specifically intended to illustrates exemplary locations of aground conductor in a shielded electrical cable according to an aspectof the present invention. Shielded electrical cable 5002 is similar toshielded electrical cable 4402 described above and illustrated in FIG.24, but includes ground conductors 5012 in various exemplary locations.Ground conductors 5012 extend in substantially the same direction asinsulated conductors 5006 of conductor sets 5004 and are positionedbetween shielding film 5008 and carrier film 5046. One ground conductor5012 is included in a parallel portion 5008″ of shielding film 5008 andthree ground conductors 5012 are included in a conductor set 5004. Oneof these three ground conductors 5012 is positioned between insulatedconductors 5006 and shielding film 5008 and two of these three groundconductors 5012 and insulated conductors 5006 are arranged generally ina single plane.

FIGS. 28a-28d illustrate various exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention. FIGS.28a-28d are specifically intended to illustrate various examples ofpartial coverage of the conductor set by the shielding film without thepresence of a carrier film. The amount of coverage by the shielding filmvaries between the embodiments. In the embodiment illustrated in FIG.28a , the conductor set has the most coverage. In the embodimentillustrated in FIG. 28d , the conductor set has the least coverage. Inthe embodiments illustrated in FIGS. 28a and 28b , more than half of theperiphery of the conductor set is covered by the shielding film. In theembodiment illustrated in FIG. 28c , about half of the periphery of theconductor set is covered by the shielding film. In the embodimentillustrated in FIG. 28d , less than half of the periphery of theconductor set is covered by the shielding film. A greater amount ofcoverage provides better electromagnetic interference (EMI) isolationand reduced signal attenuation (resulting from a reduction in theproximity effect). Although in these embodiments, a conductor setincludes two substantially parallel longitudinal insulated conductors,in other embodiments, a conductor set may include one or more than twosubstantially parallel longitudinal insulated conductors.

Referring to FIG. 28a , shielded electrical cable 5102 includes aconductor set 5104 and a shielding film 5108. Conductor set 5104includes two longitudinal insulated conductors 5106. Shielding film 5108includes parallel portions 5108″ extending from both sides of conductorset 5104. Parallel portions 5108″ cooperatively define a generallyplanar shielding film. Shielding film 5108 further includes a coverportion 5108′″ partially covering conductor set 5104. Cover portion5108′″ includes concentric portions 5108′ substantially concentric withcorresponding conductor 5106. Cover portion 5108′″ of shielding film5108 covers the bottom side and the entire left and right sides ofconductor set 5104.

Referring to FIG. 28b , shielded electrical cable 5202 is similar toshielded electrical cable 5102 described above and illustrated in FIG.28a . However, in shielded electrical cable 5202, cover portion 5208′″of shielding film 5208 covers the bottom side and more than half of theleft and right sides of conductor set 5204.

Referring to FIG. 28c , shielded electrical cable 5302 is similar toshielded electrical cable 5102 described above and illustrated in FIG.28a . However, in shielded electrical cable 5302, cover portion 5308′″of shielding film 5308 covers the bottom side and about half of the leftand right sides of conductor set 5304.

Referring to FIG. 28d , shielded electrical cable 5402 is similar toshielded electrical cable 5102 described above and illustrated in FIG.28a . However, in shielded electrical cable 5402, cover portion 5408′″of shielding film 5408 covers the bottom side and less than half of theleft and right sides of conductor set 5404.

As an alternative to a carrier film, for example, shielded electricalcables according to aspects of the present invention may include anoptional non-conductive support. This support may be used to completephysical coverage of a conductor set and add to the mechanical stabilityof the shielded electrical cable. FIGS. 29a-29d illustrate variousexemplary embodiments of a shielded electrical cable according toaspects of the present invention including a non-conductive support.Although in these embodiments, a non-conductive support is used with aconductor set that includes two substantially parallel longitudinalinsulated conductors, in other embodiments, a non-conductive support maybe used with a conductor set that includes one or more than twosubstantially parallel longitudinal insulated conductors, or with aground conductor. The support may include any suitable polymericmaterial, including but not limited to polyester, polyimide,polyamide-imide, polytetrafluoroethylene, polypropylene, polyethylene,polyphenylene sulfide, polyethylene naphthalate, polycarbonate, siliconerubber, ethylene propylene diene rubber, polyurethane, acrylates,silicones, natural rubber, epoxies, and synthetic rubber adhesive. Thesupport may include one or more additives and/or fillers to provideproperties suitable for the intended application.

Referring to FIG. 29a , shielded electrical cable 5502 is similar toshielded electrical cable 5102 described above and illustrated in FIG.28a , but further includes a non-conductive support 5548 partiallycovering conductor set 5504 opposite cover portion 5508′″ of shieldingfilm 5508. Support 5548 covers essentially the entire top side ofconductor set 5504, essentially fully enclosing insulated conductors5506. Support 5548 includes a generally planar top surface 5548 a. Topsurface 5548 a and parallel portions 5508″ are substantially coplanar.

Referring to FIG. 29b , shielded electrical cable 5602 is similar toshielded electrical cable 5202 described above and illustrated in FIG.28b , but further includes a non-conductive support 5648 partiallycovering conductor set 5604 opposite cover portion 5608′″ of shieldingfilm 5608. Support 5648 only partially covers the top side of conductorset 5604, leaving insulated conductors 5606 partially exposed.

Referring to FIG. 29c , shielded electrical cable 5702 is similar toshielded electrical cable 5302 described above and illustrated in FIG.28c , but further includes a non-conductive support 5748 partiallycovering conductor set 5704 opposite cover portion 5708′″ of shieldingfilm 5708. Support 5748 covers essentially the entire top side ofconductor set 5704, essentially fully enclosing insulated conductors5706. At least a portion of support 5748 is substantially concentricwith insulated conductors 5706. A portion of support 5748 is disposedbetween insulated conductors 5706 and shielding film 5708.

Referring to FIG. 29d , shielded electrical cable 5802 is similar toshielded electrical cable 5402 described above and illustrated in FIG.28d , but further includes a non-conductive support 5848 partiallycovering conductor set 5804 opposite cover portion 5808′″ of shieldingfilm 5808. Support 5848 only partially covers the top side of conductorset 5804, leaving insulated conductors 5806 partially exposed. A portionof support 5848 is disposed between insulated conductors 5806 andshielding film 5808.

The following items are exemplary embodiments of a shielded electricalcable according to aspects of the present invention.

Item 1 is a shielded electrical cable comprising a conductor setincluding one or more substantially parallel longitudinal insulatedconductors; and a shielding film including a cover portion partiallycovering the conductor set, and parallel portions extending from bothsides of the conductor set.

Item 2 is the shielded electrical cable of item 1, wherein the parallelportions cooperatively define a generally planar shielding film.

Item 3 is the shielded electrical cable of item 1, wherein the coverportion includes a concentric portion substantially concentric with atleast one of the conductors.

Item 4 is the shielded electrical cable of item 1 further comprising anon-conductive carrier film including a cover portion partially coveringthe conductor set opposite the cover portion of the shielding film, andparallel portions extending from both sides of the conductor set anddisposed opposite the parallel portions of the shielding film.

Item 5 is the shielded electrical cable of item 4, wherein the coverportion of the carrier film includes a concentric portion substantiallyconcentric with at least one of the conductors.

Item 6 is the shielded electrical cable of item 1 further comprising atleast one longitudinal ground conductor extending in substantially thesame direction as the one or more insulated conductors.

Item 7 is the shielded electrical cable of item 6, wherein the groundconductor makes direct electrical contact with the shielding film in atleast one location along its length.

Item 8 is the shielded electrical cable of item 6, wherein the groundconductor makes indirect electrical contact with the shielding film inat least one location along its length.

Item 9 is the shielded electrical cable of item 6, wherein the groundconductor extends beyond at least one of the ends of the shielding film.

Item 10 is the shielded electrical cable of item 6, wherein the groundconductor is included in the conductor set.

Item 11 is the shielded electrical cable of item 6, wherein the groundconductor is included in the parallel portion.

Item 12 is the shielded electrical cable of item 1, wherein theconductor set and shielding film are cooperatively configured in animpedance controlling relationship.

Item 13 is the shielded electrical cable of item 1 further comprising anon-conductive support partially covering the conductor set opposite thecover portion of the shielding film.

Item 14 is the shielded electrical cable of item 13, wherein the supportincludes a concentric portion substantially concentric with at least oneof the conductors.

Item 15 is a shielded electrical cable comprising a plurality of spacedapart conductor sets arranged generally in a single plane, eachconductor set including one or more substantially parallel longitudinalinsulated conductors; and a shielding film including a plurality ofcover portions partially covering the conductor sets, and a parallelportion disposed between adjacent conductor sets and configured toelectrically isolate the adjacent conductor sets from each other.

Item 16 is the shielded electrical cable of item 15, wherein theparallel portion is positioned at a depth that is greater than about onethird of the diameter of the insulated conductors.

Item 17 is the shielded electrical cable of item 15, wherein theparallel portion is positioned at a depth that is greater than about onehalf of the diameter of the insulated conductors.

Although specific embodiments have been illustrated and described hereinfor purposes of description of the preferred embodiment, it will beappreciated by those of ordinary skill in the art that a wide variety ofalternate and/or equivalent implementations calculated to achieve thesame purposes may be substituted for the specific embodiments shown anddescribed without departing from the scope of the present invention.Those with skill in the mechanical, electro-mechanical, and electricalarts will readily appreciate that the present invention may beimplemented in a very wide variety of embodiments. This application isintended to cover any adaptations or variations of the preferredembodiments discussed herein. Therefore, it is manifestly intended thatthis invention be limited only by the claims and the equivalentsthereof.

What is claimed is:
 1. A shielded electrical cable comprising: aconductor set including one or more substantially parallel longitudinalinsulated conductors; a shielding film disposed around the conductorset; two non-conductive polymeric layers disposed around the conductorset and including concentric portions substantially concentric with atleast one of the insulated conductors having a conductor having a firstcross-sectional area, and parallel portions wherein the twonon-conductive polymeric layers are substantially parallel to eachother; and an adhesive layer disposed between the two non-conductivepolymeric layers and bonding the concentric portions of the twonon-conductive polymeric layers to the conductor set and the parallelportions of the two non-conductive polymeric layers to each other; and atransition portion providing a gradual transition between the concentricportions and the parallel portions of the two non-conductive polymericlayers, the transition portion comprising a second cross-sectional areadefined as an area between first transition points where a thickness ofthe adhesive layer becomes greater than a thickness of the adhesivelayer in the concentric portions of the two non-conductive polymericlayers and second transition points where a thickness of the adhesivelayer becomes greater than a thickness of the adhesive layer in theparallel portions of the two non-conductive polymeric layers, the secondcross-sectional area being equal to or smaller than the firstcross-sectional area.
 2. The shielded electrical cable of claim 1,wherein the second cross-sectional area is smaller than the firstcross-sectional area.
 3. The shielded electrical cable of claim 1,wherein the second cross-sectional area is substantially the same alongthe length of the cable.
 4. The shielded electrical cable of claim 1,wherein the shielded electrical cable includes transition portionspositioned on both sides of the conductor set.
 5. The shieldedelectrical cable of claim 1, wherein the at least one of the insulatedconductors has an insulation thickness, and wherein the transitionportion has a lateral length defined as a length between the firsttransition points, wherein the lateral length is less than theinsulation thickness.
 6. The shielded electrical cable of claim 1,wherein the transition portion has a lateral length defined as a lengthbetween the first transition points, and wherein the lateral length isless than a diameter of the conductor.
 7. The shielded electrical cableof claim 1 comprising a characteristic impedance that is within 5 to 10%of a target impedance value over a length of 1 meter.
 8. The shieldedelectrical cable of claim 1, wherein the two non-conductive polymericlayers include parallel portions positioned on each side of theconductor set.